A cooling method is known for a battery pack that accommodates cells, having a blower inside a casing where a heat exchanger performing a refrigeration cycle is provided, controlling the temperature inside the casing by the heat exchanger that is temperature-controlled using a cooling capacity of the refrigeration cycle.
This method is expensive and the structure is complicated because it requires the refrigeration cycle.
That is, the overall cost of the system increases and it becomes an obstacle to production or sales when the refrigeration cycle is required.
Further, since there are entry and exit points for refrigerant pipes in addition to wires, special treatments and structures are required for securing tightness, thus resulting with further increase in cost.
Therefore, as disclosed in Japanese Patent Application Laid-Open Publication No. 2010-33799, an electric power storage device that allows air to flow inside the battery pack from the outside has been used.
The device in the Publication '799 has a plurality of electric power storage units, and disposes a first electric power storage unit and a second electric power storage unit side by side for efficiently adjusting the temperature of electric power storage modules in each electric power storage unit.
Further, each electric power storage unit in the electric power storage device of the Publication '799 has the electric power storage module having a plurality of storage elements, and a supply duct that supplies a heat exchange medium, which exchanges heat between the storage elements, to the electric power storage module.
Moreover, each electric power storage unit has a discharge duct for discharging the heat exchange medium that has exchanged heat with the storage elements.
Then, the exhaust ducts of the first and second electric power storage units arranged side by side.
As a result, in the Publication '799, air sucked from the outside flows between the cells, and the air is discharged to the outside from an exhaust passage.
However, according to a techniques disclosed in the Publication '799, since the air-cooled battery pack that cools the cells with air is cooled in a so-called open type, noise occurs and propagates outside as a trade-off of the cooling.
Further, dust enters easily into the battery pack. Furthermore, condensation easily occurs inside the battery pack. Moreover, there is a problem that it is necessary to consider the effect of exhaust air in order to ensure comfort.